Systems for the detection of chemical and biological weaponry are of increasing international interest. A biological weapon incorporates an organism (bacteria, virus or other disease-causing organism) or toxin found in nature as a weapon of war. Biological warfare agents of critical concern include bacterial spores such as Bacillus anthracis (anthrax), Clostridium tetani (tetanus), and Clostridium Botulinum (botulism). Particularly Bacillus bacteria and Clostridium bacteria form bacterial spores.
Dipicolinic acid (pyridine 2,6 dicarboxylic acid) (DPA) is a major component of bacterial spores and it is unique in that it has only been found in bacterial spores. Up to 15% of a spore's dry weight may consist of DPA complexed with calcium ions (CaDPA).